U.S. patent number 9,314,625 [Application Number 14/023,278] was granted by the patent office on 2016-04-19 for integrated implantable hearing device, microphone and power unit.
This patent grant is currently assigned to Cochlear Limited. The grantee listed for this patent is Cochlear Limited. Invention is credited to James R Easter, James Frank Kasic, II.
United States Patent |
9,314,625 |
Kasic, II , et al. |
April 19, 2016 |
Integrated implantable hearing device, microphone and power
unit
Abstract
An implantable hearing unit is provided that includes an
implantable microphone, a rechargeable power storage device and a
speech signal processor. The hearing unit further includes a signal
coupling device that is adapted for electrical interconnection to
an implantable auditory stimulation device, which is operative to
stimulate an auditory component of a patient. Such a stimulation
device may include cochlear implants, brain stem stimulation
systems, auditory nerve stimulation systems, and middle or inner
ear transducer systems. The signal coupling device is operative to
provide processed drive signals from the signal processor to the
stimulation device as well provide power from the power storage
device to operate the stimulation device. In one arrangement, the
signal coupling device is a wireless coupling between first and
second coils. In such an arrangement, the hearing unit may be
utilized with an existing implanted stimulation device to make that
device a fully implanted hearing system.
Inventors: |
Kasic, II; James Frank
(Boulder, CO), Easter; James R (Lyons, CO) |
Applicant: |
Name |
City |
State |
Country |
Type |
Cochlear Limited |
Macquarie University, NSW |
N/A |
AU |
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Assignee: |
Cochlear Limited (Macquarie
University, NSW, AU)
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Family
ID: |
36917055 |
Appl.
No.: |
14/023,278 |
Filed: |
September 10, 2013 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20140012350 A1 |
Jan 9, 2014 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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11356434 |
Feb 16, 2006 |
8550977 |
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60653415 |
Feb 16, 2005 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61N
1/3787 (20130101); A61N 1/37223 (20130101); H04R
25/554 (20130101); H04R 25/606 (20130101); H04R
2225/67 (20130101); H04R 2225/021 (20130101); H04R
2225/31 (20130101); H04R 25/505 (20130101); A61N
1/36038 (20170801); H04R 2420/07 (20130101) |
Current International
Class: |
A61N
1/36 (20060101); H04R 25/00 (20060101) |
Field of
Search: |
;600/25 ;607/57 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Matthews; Christine H
Attorney, Agent or Firm: Hauptman Ham, LLP
Parent Case Text
RELATED APPLICATIONS
The present application is a divisional of and claims priority to
U.S. patent application Ser. No. 11/356,434, filed Feb. 16, 2006,
which in turn claims priority to U.S. Provisional Patent
Application No. 60/653,415, the present application also claiming
priority thereto, the disclosures of which are hereby incorporated
by reference herein in entirety.
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims priority under 35 U.S.C. .sctn.119 to U.S.
Provisional Application No. 60/653,415 entitled "Integrated
Implantable Hearing Device Microphone and Power Unit" and having a
filing date of Feb. 16, 2005, the entire contents of which are
incorporated by reference herein.
Claims
What is claimed:
1. An implantable hearing prosthesis, comprising: a first
implantable apparatus including an implantable signal processor
configured to generate drive signals for activating an implantable
auditory stimulation device; a second implantable apparatus
including the implantable auditory stimulation device; and a
flexible communications device extending between said first
implantable apparatus and said second implantable apparatus; and a
selectively attachable and detachable connector configured to
mechanically connect and disconnect the communications device from
one of the first implantable apparatus or the second implantable
apparatus, wherein said first implantable apparatus further
comprises a modulator configured to modulate said drive signals
prior to said drive signals being transmitted to said implantable
stimulation device, wherein the implantable auditory stimulation
device is a cochlear electrode array configured for insertion into
a cochlea of a recipient, and said drive signals drive the cochlear
electrode array to stimulate the cochlea with electrical
current.
2. The implantable hearing prosthesis of claim 1, wherein: the
first implantable apparatus is an implantable module including: the
implantable signal processor; an implantable microphone operative
to transcutaneously receive sound and generate a microphone output
signal; and an implantable rechargeable battery for powering at
least said microphone and said processor.
3. The implantable hearing prosthesis of claim 1, wherein: said
first implantable apparatus further comprises a demodulator for
demodulating modulated drive signals.
4. The implantable hearing prosthesis of claim 1, wherein: said
connector includes only two electrical contact conductors.
5. The implantable hearing prosthesis of claim 1, wherein:
communication between the first implantable apparatus and the
second implantable apparatus is established by an inductive link,
wherein the link is established by a transmitting coil and a
receiving coil, wherein the transmitting coil is removably mated
with the receiving coil, and wherein the transmitting coil and the
receiving coil are configured to be completely implantable.
6. The implantable hearing prosthesis of claim 1, wherein: the
first implantable apparatus is configured to provide a modulated
signal modulated by the modulator to the flexible communications
device; and the flexible communications device is configured to
communicate the modulated signal from the first implantable
apparatus to the second implantable apparatus.
7. The implantable hearing prosthesis of claim 1, wherein: the
flexible communications device is configured to deliver modulated
signals modulated by the modulator from the first implantable
apparatus to the second implantable apparatus.
8. The implantable hearing prosthesis of claim 1, wherein: the
implantable hearing prosthesis is configured to modulate said drive
signals prior to said drive signals being transmitted to said
second implantable apparatus via said flexible communications
device.
9. A method, comprising: positioning a first component of an
implantable hearing prosthesis at a first subcutaneous location in
a recipient, said first component including an implantable auditory
stimulation device; positioning a second component of the
implantable hearing prosthesis at a second subcutaneous location in
a recipient, the second component including an implantable signal
processor configured to generate drive signals for activating the
implantable auditory stimulation device; releasably mechanically
connecting said first and second components utilizing a
communications conductor configured to establish communication
between the first and second component; evoking a hearing percept
as a result of transmission of drive signals from the second
component to the first component through the communications
conductor; and after evoking the hearing percept, removing the
second component from the recipient and locating a third component
at a subcutaneous location in the recipient, the third component
including a third implantable signal processor configured to
generate drive signals for causing the implantable auditory
stimulation device to evoke a hearing percept.
10. The method of, claim 9, further comprising: releasing the
communications conductor from at least one of the first or second
components; and releasably mechanically connecting the first and
third components utilizing the communications conductor.
11. The method of claim 9, wherein: the first component includes a
receiver and an intracochlear electrode; and the second component
is a module that includes an implantable microphone, a rechargeable
power supply and a processor.
12. The method of claim 9, further comprising: subcutaneously
routing the communications conductor to a location extending
between said first and second components.
13. The method of claim 11, further comprising: transmitting from
said second component to said first component, through said
communications conductor, signals for use in actuating said
intracochlear electrode.
14. The method of claim 9, wherein the implantable auditory
stimulation device includes a cochlear electrode array including at
least 22 electrodes, and wherein the action of releasably
mechanically connecting comprises establishing communication
between said first and second components via only two
conductors.
15. The method of claim 9, further comprising: after releasably
mechanically connecting said first and second components, releasing
the connection while at least the first component is implanted in a
recipient.
16. A method, comprising: positioning a first component of an
implantable hearing prosthesis at a first subcutaneous location in
a recipient, said first component including an implantable auditory
stimulation device; positioning a second component of the
implantable hearing prosthesis at a second subcutaneous location in
a recipient, the second component including an implantable signal
processor configured to generate drive signals for activating the
implantable auditory stimulation device; and releasably
mechanically connecting said first and second components utilizing
a communications conductor configured to establish communication
between the first and second component, wherein the action of
releasably mechanically connecting said first and second components
utilizing a communications conductor configured to establish
communication between the first and second component occurs while
at least the first component is implanted in a recipient.
17. An implantable hearing prosthesis, comprising: a first
implantable apparatus including an implantable signal processor
configured to generate drive signals for activating an implantable
auditory stimulation device; a second implantable apparatus
including the implantable auditory stimulation device; and a
flexible communications device extending between said first
implantable apparatus and said second implantable apparatus; and a
selectively attachable and detachable connector configured to
mechanically connect and disconnect the communications device from
one of the first implantable apparatus or the second implantable
apparatus, wherein said first implantable apparatus further
comprises a modulator configured to modulate said drive signals
prior to said drive signals being transmitted to said implantable
stimulation device; and wherein the implantable hearing prosthesis
further comprises: a third implantable apparatus including an
implantable microphone; and a second communications device separate
from the flexible communications device, the second communications
device configured to communicate electrical signals from the third
implantable apparatus to the first implantable apparatus.
Description
FIELD OF THE INVENTION
The present invention relates to implanted hearing devices, and
more particularly, to an implanted microphone and power unit
assembly for use with an implantable stimulation device attached to
a patient's auditory system.
BACKGROUND OF THE INVENTION
Implantable hearing devices stimulate internal components of the
auditory system and are generally classified into one of two types,
namely fully implantable hearing aids and semi-implantable hearing
aids. In a fully implantable hearing device, the entire device is
implanted. In a semi-implantable hearing device, some of the
components, typically the microphone, power supply, and speech
signal processor, are externally worn, while the
transducer/stimulator and key support functions are implanted
within the auditory system. The externally worn portion
communicates transcutaneously with the implanted portion to provide
audio signals that the implanted portion uses to stimulate to the
auditory system.
By way of example, one type of implantable transducer includes an
electromechanical transducer having a magnetic coil that drives a
vibratory actuator. The actuator is positioned to interface with
and stimulate the ossicular chain of the patient via physical
engagement. (See e.g., U.S. Pat. No. 5,702,342). In this regard,
one or more bones of the ossicular chain are made to mechanically
vibrate, which causes the ossicular chain to stimulate the cochlea
through its natural input, the so-called oval window.
Implanted hearing devices are typically used by individuals with
significant loss of hearing function or damage to the auditory
system. As a result, they differ in the manner by which the signal
is processed and delivered to the patient. The processing step,
known in the art as Speech Signal Processing ("SSP"), may include a
number of steps such as amplification, frequency shaping,
compression, etc. The steps in the SSP are determined by the design
of the hearing device, while the particular internal values used in
the steps are generated from prescriptive parameters determined by
an audiologist. Once a speech processor receives an audio signal
(e.g., from a microphone) that is indicative of ambient acoustic
signals, an drive signal produced and provided to an implanted
stimulation device that stimulates the hearing impaired person's
auditory system. The auditory stimulation may be done acoustically,
mechanically, or electrically as a function of the type and
severity of the hearing loss in the hearing impaired
individual.
The type and/or severity of hearing loss may dictate what type of
implantable hearing device may be beneficial to an impaired person.
Heretofore, this has required that many impaired persons utilize
semi-implantable hearing devices. Some surveys of current and
potential hearing instrument wearers show that fully implantable or
non-visible hearing devices have greater consumer acceptance. That
is, there is some belief that fully implantable hearing devices may
avoid stigmatizing cosmetics associated with semi-implantable
devices.
SUMMARY OF THE INVENTION
The present invention is generally directed to the provision of an
implantable hearing unit that includes an implantable microphone, a
rechargeable power storage device, a speech signal processor (SSP).
The hearing unit further includes a signal coupling device that is
adapted for electrical interconnection to an implanted auditory
stimulation device, which is operative to stimulate an auditory
component of a patient. Such an implanted auditory stimulation
device may include, without limitation, cochlear implants, brain
stem stimulation systems, auditory nerve stimulation systems, and
middle ear or inner ear transducer systems. Stated otherwise, the
stimulation device may be any device that is operative to
acoustically, electrically and/or mechanically stimulate an
internal component of the auditory system of a patient.
As noted, the hearing unit incorporates the implantable microphone,
the rechargeable power storage device and a signal processor. These
components may be housed in a common implant housing, or these
components may be separate implantable devices that are
electrically connectable. The hearing unit may also incorporate
additional components such as, but not limited to, memory devices,
rectifying circuiting, etc. In any case, the implantable microphone
is operative to transcutaneously receive sound and generate an
output signal. The processor utilizes the output signal to generate
a drive signal for use in actuating an implantable auditory
stimulator device. As may be appreciated, the drive signal may be
tailored to a particular stimulation device. The power storage
device is operative to power the hearing unit as well as provide
operating power to the auditory stimulation device via the signal
coupling device. Further, the power storage device (e.g., one or
more batteries) is rechargeable using transcutaneously received
signals from an external source. Such signals may include
electromagnetic signals (e.g., RF signals) as well as magnetic
signals (e.g., inductive signals). Accordingly, the hearing unit
may incorporate a receiver (e.g., coil or antenna) to receive such
signals and/or a transmitter to transmit signals to an external
receiver. To provide continuous operation for extended periods of
time, the rechargeable power storage device may have a capacity of
at least 20 mW/h, more preferably at least 50 mW/h and even more
preferably at least 100 mW/h. However, it will be appreciated that
use of the hearing unit with different stimulation devices may
result in different power requirements. Accordingly, capacity of
the power supply may be selected in accordance with needs of a
particular system.
The signal coupling device is operative to provide processed drive
signals from the signal processor to the implantable stimulation
device. Furthermore, the signal coupling device is also operative
to provide power from the power storage device to the implantable
stimulation device. The use of the signal coupling device to
electrically power and provide drive signals to an implanted
stimulation device may allow for independent/separate subcutaneous
placement of those components. This may simplify placement of the
stimulation device relative to an auditory component of the
patient. Further, the signal coupling device may allow for
selective removal of the implantable hearing unit without
disturbing the implantable stimulation device.
According to a first aspect of the present invention, an
implantable hearing unit is provided that may be utilized with any
of a variety of different implantable stimulation devices. In this
first aspect, the signal coupling device is a wireless signal
transmitter utilized to interconnect the hearing unit to the
implantable stimulation device. That is, according to the first
aspect a subcutaneously wireless link is established between two
implantable devices, namely, an implanted hearing unit, which
includes a microphone, power storage device and processor, and an
implantable stimulation device. The wireless link between the
implanted hearing unit and the implantable stimulation device
electrically interconnects those devices for power transfer
purposes as well as for transferring processed signals (e.g., drive
signals) for use in auditory stimulation. In one arrangement, the
wireless link comprises an inductive link. In such an arrangement,
each device will typically include a coil for use in inductively
transmitting/receiving signals (e.g., drive signals and/or power).
Such signals may be modulated and/or demodulate in any appropriate
manner including, without limitation, AM or FM modulation for
analog signals as well as sigma-delta or pulse-width modulation for
digital signals. FIG. 2B depicts a modulator 151 in black-box
format that accomplishes the aforementioned modulation.
In one arrangement, use of the wireless signal coupling device with
the implantable hearing unit may allow for retrofitting existing
semi-implanted hearing instruments. Accordingly, such instruments
may be converted from partially implanted hearing instruments into
fully implanted hearing instruments. In this regard, the signal
processor of the implantable hearing unit may be programmed to
provide drive signals that are compatible with an existing
implantable stimulation device (e.g., cochlear stimulation devices
and/or middle ear devices). In such an application, removal of an
implantable stimulation device already interconnected to a
component of a patient's auditory system is not required to convert
the device to a fully implantable hearing system. As will be
appreciated, different implantable stimulation devices may be
interconnected to auditory components in a manner that makes their
removal undesirable and/or potentially damaging. For instance,
removal of an electrode array of a cochlear implant would require
surgery under general anesthesia and may cause damage to the
cochlea thereby rendering the cochlea unable to utilize such an
implant. Likewise, some middle ear transducers are affixed to one
or more of the ossicle bones and may require removal of one or more
ossicle bones, or cause damage to the ossicles, upon explanation.
In either case, it is undesirable to remove implanted stimulation
device.
However, many semi-implantable devices already include a wireless
receiver (e.g., coil) that is operative to receive transcutaneous
signals from an external speech processing unit. Accordingly, a
wireless transmitter (e.g., an inductive coil) of the implantable
hearing unit may be positioned relative to the wireless receiver of
the implantable stimulation device upon implantation of the
implantable hearing unit. This may effectively retrofit an existing
semi-implantable hearing instrument such that it becomes a fully
implantable hearing instrument, in a minimally invasive procedure,
preferably under local anesthesia. To permit such positioning, the
wireless transmitter may be interconnected to the hearing unit
using a flexible connector.
In another arrangement of the present aspect, the wireless signal
coupling device may be utilized with originally manufactured
implantable hearing systems having two separate implantable
portions. In this regard, a first portion of the implantable system
may comprise the implantable stimulation device, which may be
intended for long term or substantially permanent implantation. A
second portion of implantable system may comprise the hearing unit
that supports power, microphone and speech processing capabilities.
The second portion of the implantable system may be conveniently
located such that is more easily accessible for replacement and/or
upgrade. Preferably, the second portion may be accessible under
local anesthesia. Likewise, the wireless signal coupling device may
permit the first portion of the implantable system to be located
relative to a given auditory component with less concern about
future access. In any case, the two-portion fully implantable
system that utilizes a wireless signal coupling device may permit
easy access and servicing of the hearing unit without disturbing
the stimulation device; thus, the difficulty and risk of disturbing
the delicate structures of the middle or inner ear may be
avoided.
According to another aspect of the present invention, an
implantable module or hearing unit, which provides power,
microphone and signal processing functions, is interconnected to an
implantable cochlear stimulation device by a conductive signal
coupling device. Such a conductive signal coupling device may
include a flexible communications wire. Such a flexible
communications wire may facilitate positioning of the hearing unit
of a stimulation device. Importantly, the conductive signal
coupling device includes a detachable connector that allows for
selective disconnecting of the implantable hearing unit and the
implantable cochlear stimulation device. As will be appreciated,
the cochlear stimulation device will include an electrode array
that is adapted for insertion into the cochlea of the patient. Once
inserted into the cochlea, it is desirable that disturbance of the
electrode array be minimized. Accordingly, use of the selectively
detachable connector permits removal of the implantable hearing
unit without removal or disturbance of the implantable cochlear
stimulation device.
Any appropriate conductive signal coupling device may be utilized.
Generally, the conductive signal coupling device will include at
least a first communications wire that extends from one of the
implantable hearing unit or the implantable stimulation device.
Such a communications wire extending from one of the implantable
devices may plug into the other device, or, communications wires
from each device may be connected by a connector disposed between
the devices. The connector may be of any appropriate type. In one
embodiment, a pacemaker-style, or "IS-1" connector is utilized.
However, it will be appreciated that any connector that is
operative for use in an implantable environment may be utilized.
While any appropriate communications wire(s) may be used to
interconnect the implantable hearing unit and the implantable
stimulation device, it may be desirable to reduce the number of
conductors (e.g., leads) interconnecting the two implantable
devices to simplify the mechanical connector. For instance, in one
embodiment a two conductor communications wire may be utilized.
In order to transmit appropriate levels of data between the
implantable hearing unit and the implantable stimulation device,
especially when using a reduced number of conductors, modulation
and demodulation of the signals may be required. As will be
appreciated, some implantable stimulation devices utilized multiple
channels and or electrodes (e.g., 24 electrodes) for stimulation
purposes. In this regard, it may be necessary to convey a
relatively large quantity of drive signal information for use in
stimulating patient auditory component. Compression, modulation
and/or demodulation of signals sent across communications wire may
be required. Examples of such modulation in the modulation schemes
include, without limitation, Frequency Division Multiplexing (FDM)
and Time division Multiplexing (TDM).
According to another aspect of the present invention, a method is
provided for wirelessly interconnecting an implantable hearing unit
with an implantable stimulation device. The method includes the
steps of positioning an implantable hearing unit relative to an
implantable stimulation device. Once positioned, a wireless signal
coupler generates a wireless link that electrically interconnects
the hearing unit to the stimulation device to permit the
transmission of power and drive signals therebetween. Accordingly,
once the implantable hearing unit is wirelessly interconnected to
the implantable stimulation device, the hearing unit may generate
drive signals and provide such drive signals to the stimulation
device via a subcutaneous wireless link. In conjunction with
providing drive signals, the hearing unit may also provide power
over to the wireless link. The provided power may allow the
stimulation device to operate and utilizes the drive signal to
stimulate an auditory component of a patient.
The step of positioning may entail positioning a wireless
transmitter associated with the implantable hearing unit relative
to a wireless receiver associated with the implantable stimulator.
For instance, the wireless transmitter and wireless receiver may be
disposed in a substantially face-to-face relationship such that an
inductive coupling may exist therebetween. However, it will be
appreciated that the wireless transmitter and wireless receiver
need not be in direct contact and may be separated. What is
important is that the wireless transmitter and wireless receiver
are operative to subcutaneously exchange signals.
The step of positioning may be performed during a surgical
procedure wherein one or both of the implantable hearing unit and
implantable stimulation device are implanted. Alternatively, step
the positioning may be performed where the implantable hearing unit
is implanted relative to a previously implanted stimulation
device.
According to another aspect of the present invention, a method for
electrically interconnecting first and second separate modules of a
fully implantable cochlear hearing instrument is provided. The
method includes positioning a cochlear stimulation device (e.g., a
first module) relative to the first subcutaneous location on the
body of a patient (e.g., relative to the cochlea). The method
further includes positioning an implantable hearing unit (e.g., a
second module) relative to a second subcutaneous location on the
body of a patient. Once the cochlear stimulation device and the
implantable hearing unit are positioned relative to the first and
second subcutaneous locations, a signal coupling device, such as a
communications conductor or wire, is subcutaneously routed between
the implanted hearing unit and implanted cochlear stimulation
device. The communications wire may releasably connect the
implantable hearing unit and stimulation device to permit removal
of one module without requiring removal of the other module.
According to another aspect of the present invention, a method for
use with an implantable auditory stimulation device is provided.
The method includes generating a drive signal at a first
subcutaneous implant module where the drive signal is operative to
actuate an implantable auditory stimulation device. The method
further includes wirelessly transmitting the drive signal from the
first subcutaneous implant module to a second subcutaneous implant
module associated with an implantable auditory stimulation device.
Accordingly, the method may further include actuating the auditory
stimulation device according to the drive signal. Generating the
drive signal may further include receiving sound at a subcutaneous
microphone and generating an output associated with that sound.
This microphone output may then be processed to generate the drive
signal.
Wirelessly transmitting the drive signal may include generating an
inductive coupling between the first module and the second module
wherein magnetic signals may be exchanged therebetween or creating
an RF link between these modules such that electromagnetic signals
may be exchanged therebetween. In any case, the method may further
include wirelessly transmitting power from a power supply
associated with the first implant module to the second implant
module. Preferably, this power supply should be sufficient to run
the second implant module and an associated auditory stimulation
device associated therewith. In one arrangement, wirelessly
transmitting power may include transmitting power sufficient to
operate the second module and the auditory stimulation device for
at least eight hours. In a further arrangement, the transmitted
power may be sufficient to operate the device for at least 12 hours
and, in a yet further arrangement, at least 16 hours.
In order to provide power for the second implant module, the method
may further include recharging the power supply associated with the
first implant module. Such recharging may occur periodically and
may entail the transcutaneous receipt of at least one of
electromagnetic signals and magnetic signals. In any case, the
received signals are utilized to charge the power supply.
Accordingly, it will be appreciated that, in order to provide a
continuous power supply for a predetermined period of time, it may
further include the selection of a power supply having a
predetermined capacity, wherein that capacity allows for a
continuous expected discharge over the period of time.
The drive signals that are generated by the first implant module
may include signals that are specific to a given implantable
stimulation device. For instance, such signals may include signals
that may be utilized for actuating an intracochlear electrode, a
middle ear transducer, an inner transducer, etc.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a semi-implantable cochlear implant;
FIG. 2A illustrates an implantable portion of a cochlear implant
and an implantable hearing unit.
FIG. 2B illustrates a schematic diagram of the components of FIG.
2A.
FIG. 3 illustrates the implantable portion of the cochlear implant
and the implantable hearing unit of FIG. 2 in an overlying
relationship.
FIGS. 4 and 5 illustrate a fully implantable cochlear implant
having two separate implantable modules that are interconnected
with a detachable communications wire.
FIG. 6 illustrates a cranial placement of the components of FIG.
2A.
DETAILED DESCRIPTION OF THE INVENTION
Reference will now be made to the accompanying drawings, which at
least assist in illustrating the various pertinent features of the
present invention. In this regard, the following description of a
hearing instrument is presented for purposes of illustration and
description. Furthermore, the description is not intended to limit
the invention to the form disclosed herein. Consequently,
variations and modifications commensurate with the following
teachings, and skill and knowledge of the relevant art, are within
the scope of the present invention. The embodiments described
herein are further intended to explain the best modes known of
practicing the invention and to enable others skilled in the art to
utilize the invention in such, or other embodiments and with
various modifications required by the particular application(s) or
use(s) of the present invention.
FIGS. 1-3 illustrate one application of the present invention. As
illustrated, a first application is directed to converting an
existing semi-implantable hearing instrument into a fully
implantable system. However, certain aspects of the present
application have application beyond conversion of a
semi-implantable hearing system into a fully implantable system.
For instance, certain aspects may be utilized with originally
manufactured implantable hearing instruments. It will be further
noted that though the invention is shown in use for converting a
semi-implantable cochlear implant into a fully implantable cochlear
implant, the present invention may be employed in conjunction with
other semi-implantable hearing instruments as well as, including,
without limitation auditory brain stem stimulation systems,
auditory nerve stimulation systems, and middle ear transducer
systems. In this regard, the present invention has applicability
with electrical stimulation systems as well as mechanical
stimulation systems. Auditory stimulation devices that may be
utilized with aspects of the present invention include those
discussed in U.S. Pat. Nos. 5,545,219, 5,624,376 5,277,694,
5,913,376, 5,984,859, 6,315,710, 6,491,622, 6,517,476, 6,575,894,
6,676,592 and 6,726,618 the contents of which are incorporated by
reference herein. Therefore, the illustrated application is for
purposes of illustration and not limitation.
Generally, there are three main parts of the cochlear implant.
There is an implant receiver/stimulator 200 that is implanted on a
patient's skull, an electrode array 210 that extends from the
housing of the receiver/stimulator 200 into the cochlea 250, and an
external speech processing unit 220. See FIG. 1. One exemplary
receiver/stimulator is the Nucleus made by Cochlear Limited of
Australia. The external speech processing unit may comprise one or
more parts depending upon the cochlear implant. For instance, the
external speech processing unit may be an integrated behind the ear
unit that includes a microphone, a speech processor, a transmitting
coil, and a power source (e.g., batteries). Alternatively, the
external speech processing unit may include a wearable processing
unit/power unit 220 that is connected (e.g., wired) to a behind the
ear unit 224. Such a behind the ear unit will typically include a
microphone 226, a transmitting coil 228 and one or more magnets for
retentive positioning with the receiver/stimulator 200. Such a
separate processing unit/power unit 220 may be interconnected to
patients' clothes, belt, etc.
In any case, the microphone 226 worn behind the patient's ear
performs the function of the outer ear. That is, the microphone 226
picks up ambient sounds for processing. As noted, the speech
processor may be mounted behind the ear or worn externally (e.g.,
on a belt or in a pocket etc). The speech processor, based on
previous fittings selects the sounds most useful for understanding
speech and codes them electronically. The electronic codes or drive
signals are sent back to the transmitting coil 228, which is
generally located behind or beneath the microphone 226. The
transmitting coil 228 is held in place by two magnets, one located
under the skin near the receiver/stimulator 200 and the other in
the center of the behind the ear unit 224. The transmitting coil
228 sends the drive signals through the skin via inductive coupling
to a receiving coil 202 of the implanted receiver/stimulator 200.
The receiver/stimulator 200 converts the drive signals it receives
into electrical signals that it sends along the electrode array
210, which is implanted in the cochlea 250 of the user.
The electrode array 210 generally consists of a plurality of small
electrode bands (e.g., 24) arranged in a row inside an a flexible
extension. Each individual electrode has a wire connecting it to
the receiver/stimulator; each has been separately programmed to
deliver electrical signals representing sounds that can vary in
loudness and pitch. When the electrodes receive an electrical
signal, they stimulate the appropriate populations of auditory
nerve fibers, which send the messages to the brain. One advantage
of such a multi-channel cochlear implant is that speech can be
filtered into frequency bands by the speech processor and delivered
to different points along the cochlea. Generally, the more
electrodes (i.e., channels) included within the array, the better
resulting sound quality a user can expect.
The cochlea is organized so that different sound frequencies
preferentially stimulate different hair cells. (As the membrane
along the bottom of the cochlea resonates in time with the sound
vibration, hair cells at different positions along the membrane are
stimulated.) Stimulating hairs located at the base of the cochlea
produces perceptions of high-pitched sounds; stimulating hairs
located at the opposite end (apex) of the cochlea produces
perceptions of lower-pitched sounds. Accordingly, the cochlear
implant has a number of electrodes at different positions on the
cochlea and is designed to deliver stimuli to appropriate
electrodes so that high-pitched sounds cause electrodes to
stimulate hair cells towards the base of the cochlea and
low-pitched sounds cause electrodes to stimulate hair cells towards
the apex of the cochlea.
FIGS. 2A and 2B, illustrate an implantable hearing unit 100 that
may be utilized with the receiver/stimulator 200 of the
semi-implantable cochlear implant of FIG. 1 to create a fully
implantable hearing instrument. As shown, the implantable hearing
unit 100 includes a biocompatible implant housing 110 that is
adapted to be located subcutaneously on a patient's skull. The
hearing unit 100 includes a first receiving coil 118, a second
transmitting coil 122, a signal processor 150 (e.g., disposed
within the housing 100) and a microphone 120. It will be
appreciated that each coil 118 and 122 is capable of inductively
transmitting and receiving signals and that the terms `receiving
coil` and `transmitting coil` are utilized for purposes of clarity
and not by way of limitation. The receiving coil 118 is operative
to transcutaneously receive electrical power and/or programming.
Further, the coil 118 may provide information to an external
processor. The transmitting coil 122 is operative to provide
electrical power and drive signals to an implanted stimulator, as
will be more fully discussed herein.
The microphone 120 is interconnected to the implant housing 110 via
a communications wire 124. This allows the microphone 120 to be
subcutaneously positioned to receive acoustic signals through
overlying tissue. However, it will be appreciated that in other
embodiments a microphone 130, as shown in phantom, may be
integrated into the implant housing 110. The implant housing 110
may be utilized to house a number of components of the implantable
hearing unit 100.
FIG. 2B schematically illustrates one embodiment of the internal
components of the hearing unit 100 and stimulation device 200 of
FIG. 2A. However, in the illustrated embodiment the implant housing
110 houses both the receiving coil 118 and the transmitting coil
122. As shown, the implantable hearing unit 100 and the stimulation
device 200 are located subcutaneously beneath the skin 170 of a
patient. Further, the implant housing 110 also houses a number of
additional components of the hearing unit 100. Specifically, the
housing 110 includes a signal processor 150, a communications
processor 152, audio input circuitry 154, an internal power supply
or battery 140, a power management unit 142 and manufacture
specific drive logic and/or circuitry 156.
As shown, the internal battery 140 is interconnected to the power
management unit 142. The power management unit 142 is operative to
provide power for the implantable hearing unit as well as provide
necessary rectifying functionality for use in charging the internal
battery 140. Such charging utilizes transcutaneously received
signals from an external unit 160, where the signals are received
via the receiving coil 118. Of note, the hearing unit 100 may
further incorporate one or more external batteries 144, which may
be operatively interconnected to the power management unit 142.
This may allow the hearing unit 100 to have a power capacity that
permits uninterrupted use of the implant auditory stimulation
device 200 for extended periods of time.
The audio input circuitry 154 is operative to receive an output
signal from the implantable microphone 120 and provide this output
signal to the signal processor 150. The audio input circuitry 154
may perform various filtering and/or amplification processes on the
microphone output signal. In any case, the signal processor 150
utilizes the received microphone output signal for use in
generating a drive signal for receipt by the auditory stimulation
device 200. In this regard, the signal processor 150 may utilize
manufacture specific drive logic and/or circuitry to generate a
drive signal that is compatible with a particular auditory
stimulation device 200. Such a drive signal, as well as power from
the internal battery 140 and/or an external battery 144 may then be
wirelessly provided to the auditory stimulation device 200
utilizing the transmitting coil 122. Alternatively, and as will be
discussed herein, the drive signals and power may be provided to
the stimulation device 200 utilizing a conductor 320 that extends
between the housing 110 of the hearing unit 100 and the auditory
stimulation device 200.
An external unit 160, which includes a coil 162 for inductively
coupling to the receiving coil 118 of the hearing unit 100, is
utilized to provide energy to the hearing unit 100 for use in
recharging the battery or batteries of the hearing unit 100.
Further, the external unit 160 may also be operative to provide
programming instructions and/or control instructions to the hearing
unit 100. In this regard, a communications processor 152, which may
in other embodiments be incorporated into the common processor with
the signal processor 150, is operative to receive program
instructions from external unit 160 as well as provide responses to
the external unit 160. As may be appreciated, various additional or
different processing logic and/or circuitry components may be
included in the implant housing 110 as a matter of design
choice.
In the embodiment of FIGS. 2A and 2B, the signal processor 150
within the implant housing 110 communicates with the implant
receiver/stimulator 200 via a subcutaneous inductive link. More
specifically, the transmitting coil 122 of the implantable hearing
unit 100 is adapted to crate an inductive link with the receiving
coil 202 of the implant receiver/stimulator 200. Specifically, the
transmitting coil 122 is configured to be disposed in an overlying
relationship with the receiving coil 202 of the implant
receiver/stimulator 200. See FIGS. 2A and 3. In the present
embodiment, the transmitting coil 122 is interconnected to the
implant housing 100 via a flexible communications wire 126 to
permit the transmitting coil 122 to be more easily positioned
relative to the receiving coil 202 of the implant
receiver/stimulator 200. Mating magnets 108, 208 may be used to
position the coils 122, 202. Though shown in a direct face to face
relationship, it will be appreciated that the transmitting coil 122
of the implantable hearing unit 100 and the receiving coil 202 of
the implant receiver/stimulator 200 may be at least partially
separated so long as they maintain an inductive link.
During normal operation, acoustic signals are received
subcutaneously at the microphone 120 and the microphone provides
audio signals to the implantable hearing unit 100. The signal
processor 150 within the housing 110 of the implantable hearing
unit 100 processes the received audio signals to provide a
processed audio signal (e.g., a drive signal) for transmission to
the receiver/stimulator 200 via the subcutaneous inductive link
between coils 122 and 202. As will be appreciated, the implantable
hearing unit 100 may utilize digital processing techniques to
provide frequency shaping, amplification, compression, and other
signal conditioning, including conditioning based on
patient-specific fitting parameters in a manner substantially
similar to an external speech processing unit (e.g., 220 of FIG.
1). The implanted receiver/stimulator 200 receives drive signals
from the implantable hearing unit 100 that are substantially
identical to drive signals received from the external speech
processing unit 220. Accordingly, the implanted receiver/stimulator
200 converts the drive signals it receives into electrical signals
that are sent to the electrode array 210, which stimulates the
patient's cochlea and causes the sensation of sound.
To power the fully implantable hearing instrument system, the
implantable hearing unit 100 generally utilizes an external charger
unit 160 (See FIG. 2B) to recharge one or more energy storage
devices/batteries 140, 144 that may be disposed within or otherwise
connected to the implant housing 100. In this regard, the external
charger may be configured for disposition behind the ear of the
implant wearer in alignment with the receiving coil 118 of the
implant housing 100. The external charger and the implant housing
100 may each include one or more magnets to facilitate retentive
juxtaposed positioning. Such an external charger may provide power
inductively. In another arrangement, not shown, the external unit
is operative to transcutaneously transmit RF signals (e.g.
electromagnetic signals) to a receiver. In this arrangement, the
receiver may also include, for example, rectifying circuitry to
convert a received signal into an electrical signal for use in
charging the energy storage device/batteries.
As will be appreciated, the use of the inductive link between the
implantable hearing unit 100 and the receiver/stimulator 200
facilitates removal of the hearing unit 100 for servicing, upgrades
etc. In this regard, one drawback of cochlear implants is that once
electrode array 210 is inserted into the cochlea 250, subsequent
removal of the electrode array 210 may result in damage to the
cochlea 250. Accordingly, by utilizing the inductive link, the
implantable hearing unit 100 may be removed for servicing without
disturbing the receiver/stimulator 200 and/or the electrode array
210.
Of note, the system of FIGS. 1-3 may be utilized not only in
retrofit applications where a semi-implantable hearing aid is
converted into a fully implantable hearing aid, but also in new
hearing instrument systems where it may be desirable to have an
implantable portion (e.g., hearing unit 100) that is selectively
removable without disturbing a more permanently implanted device
(e.g., stimulator).
FIGS. 4 and 5 illustrate a second application of the present
invention. In this application, the implantable hearing instrument
system utilizes most of the same components of the implantable
hearing unit 100 as discussed in relation to FIGS. 2-3 above.
However, in this application the implantable hearing unit 100 is
directly electrically connected to the implantable stimulator 300.
Specifically, the stimulator 300 and implantable hearing unit 100
are connected via a communications wire 320 instead of by a
subcutaneous inductive link. In this regard, a receiving coil is
not needed for the stimulator 300 nor is a transmitting coil
required for the implantable hearing unit 100. Otherwise, the
structure and function of stimulator 300 is substantially the same
as stimulator 200. Again, an electrode array 310 extends from the
stimulator 300 and the stimulator 300 provides drive signals to the
electrode array 310 is in manner that substantially unchanged in
relation to that discussed above.
Though the stimulator 300 and implantable hearing unit 100 are
interconnected by a communications wire 320, the communications
wire 320 includes a detachable connector 340 that permits selective
detachment of the communications connection between the stimulator
300 implantable hearing unit 100. In this regard, implantable
hearing unit 100 may be detached from the stimulator 300 and its
attached electrode array 310. As noted above, it may be undesirable
after implant to remove the stimulator 300 and electrode array 310
as the potential to damage to the cochlea exists. However, it is
foreseeable that one or more components of the implantable hearing
unit 100 may require periodic maintenance, updating and/or
replacement. For instance, while it is believed that the onboard
power storage device will last for a number of years, it may
eventually need to be replaced. It is further believed that
advancements to hardware and/or software may become available in
the future and it may be desirable to replace the entire
implantable hearing unit 100 to upgrade the system. In any case,
use of the detachable connector 340 in the communications wire 330
allows for such removal and/or maintenance of the hearing unit 100
without disturbing the electrode array 320.
Of note, cochlear implants typically utilize a plurality of
electrodes that are each interconnected to be stimulator by an
individual conductor (i.e. wire). That is, a number of wires may
extend from the stimulator 300 that is equal to the number of
electrodes (e.g., 22 electrodes and 22 wires) of the cochlear
implant. However, it is generally undesirable to have a connector
340 that includes such a large number of conductive connections.
More preferably, a communications wire 320 having fewer (e.g., two)
conductors may be utilized to simplify the connector 340. A
selectively detachable connector that provides at least two
conductor connection and which is suited for implantation uses is
described in U.S. Pat. No. 6,517,476 entitled "Connector for
Implantable Hearing Aid" the contents of which are incorporated by
reference herein.
In order to properly stimulate the patient's auditory system, the
stimulator 300 must receive adequate information for all the
electrodes or channels across the communications wire 320. Use of a
two conductor wire generally requires modulating/demodulating of
the signals sent from the implantable hearing unit 100 to the
stimulator 300 to allow for adequate data transfer. For instance,
Frequency Division Multiplexing (FDM) and Time Division
Multiplexing (TDM) and or Code Division Multiplexing (CDMA)
modulating/demodulating methodologies may be utilized in order to
provide adequate information to the stimulator.
In any arrangement, (e.g., wireless connection or direct conductive
coupling) the capacity of the power storage device(s) of the
implantable hearing unit 100 will determine the length of time a
user may go between necessary recharges. The capacity of a battery
is generally stated in milliampere-hours, or mAh. This parameter
defines the length of time the battery may deliver a given rate of
current or, conversely, the maximum current deliverable over a
fixed period. Although these two measures are not strictly
interchangeable over all rates of discharge, they correspond well
enough to permit designers to selected batteries that are sized for
different applications.
It has been determined that inductive/RF transmission efficiency is
a significant factor in determining time between battery charges in
systems that utilize an inductive/RF power/signal link to provide
power and drive signals to an implanted auditory stimulation
device. The time between charges for an implantable battery
connected by such a link may be calculated as:
.eta..times. ##EQU00001## where T.sub.bc is time between charges, Q
is battery capacity, I.sub.proc is the current drain of the
processor connected to the battery, I.sub.stim is the current drain
of the auditory stimulation device driven through the link, and
.eta..sub.RF is the efficiency of the inductive/RF link.
As an example, assume that the battery capacity is 50 mAh, current
requirement for the sound processor is 1.5 mA, current requirement
for a cochlear stimulator is 2.5 mA, and inductive RF link
efficiency is 40%.
TABLE-US-00001 Battery capacity 50 mAh Current drain before RF link
(processor) 1.5 mA Current drain after RF link (stimulator) 2.5 mA
RF link efficiency 40% Resulting time between charges 6.45 hrs
The RF efficiency of 40% assumed in the example above is typical of
RF transmission architectures. The resulting time between charges
of less than 61/2 hours may be less than is desired by many users,
who may prefer that a fully implantable system permit a full day of
use without the inconvenience of recharging the implantable
battery.
User needs may thus be compromised by the energy losses associated
with inductive coupling. While the use of a conductive coupling
eliminates the inefficiency of the inductive coupling, this is not
an upgrade option for existing users. In this regard, the remaining
option to extend the time between recharge is to increase the
capacity of the battery or batteries of the implantable hearing
unit 100.
As shown above, the amount of battery capacity may be selected
based on the type of implantable auditory stimulation device
utilized and the desired time between capacity. Accordingly, for
instances where low battery capacities are sufficient, a
rechargeable battery 140 may be incorporated into the housing 110
of the implantable hearing unit 100. See FIG. 2B. This may result
in a compact hearing unit 100. For such a compact system, a
convenient location for placement of the is in the temporal region
of the skull, near the typical location of the stimulator. See FIG.
6. This location minimizes the length of exposed wires 124, 126,
and simplifies the surgical procedure.
In instances where greater battery capacity is required, a larger
battery, or multiple batteries may be utilized. Again, a
rechargeable battery or batteries may be incorporated into the
housing 110 of the implantable hearing unit 100 and/or one or more
separate implantable batteries 144 that are electrically connected
to the implantable hearing unit 100 may be utilized. As will be
appreciated, such separate implantable batteries may be detachable
such that the battery or batteries may be removed and replaced
without removing the implantable hearing unit 100. However, the use
of larger or multiple batteries may increase the size of the
implantable hearing unit making cranial location of the implantable
hearing unit problematic.
In instances in which the implantable hearing unit or implantable
batteries are too large for convenient placement on the skull,
implantable hearing unit 100, including, for example, the receiving
coil 118 and batteries may be placed subclavicularly, in a location
similar to that of an implantable pacemaker. In this arrangement,
the wire 124 and 126 extending between the hearing unit 100 and the
microphone 120 and transmitting coil 122, respectively, may be
routed subcutaneously through the soft tissues of the neck. Such an
arrangement may allow for converting an existing partially
implantable hearing instrument into a fully implantable hearing
instrument that provides full day use (e.g., 15-16 hours) between
recharges.
Those skilled in the art will appreciate variations of the
above-described embodiments that fall within the scope of the
invention. As a result, the invention is not limited to the
specific examples and illustrations discussed above, but only by
the following claims and their equivalents.
* * * * *